Description: The Transgenic Animal Services Core, based in the Department of Comparative Medicine, provides an on-campus unit where CEEH investigators can submit their constructs or their targeted embryonic stem (ES) cells to generate transgenic or gene-targeted mouse lines. The specific aims of the Core are: 1) provide resources to offset the high costs of developing transgenic animal strains for CEEH investigators who use, or intend to use, transgenic animals in research related to the Center's theme; 2) partially support maintenance and use of transgenic animal lines in research related to the Center's theme; and 3) provide limited consultation, advice, and training to inexperienced CEEH investigators wishing to establish their own transgenic animals. Services and resources currently provided by the Core include: 1) generation of transgenic and gene-targeted mice by microinjection and embryonic stem (ES) cell-targeted mutagenesis, 2) cryopreserved stocks of mouse ES cell lines of the 129 and C57BL/6 backgrounds, 3) management of genetically engineered mouse breeding colonies, 4) maintenance of genetically engineered mice free of intercurrent disease or derivation of infected strains when necessary, and 5) consultation with regard to such matters as vector design and selections of appropriate mouse background strains. Dr. Warren Ladiges has served as director of the Core since 1986.